
4
C
Package Pin Description
PACKAGE PIN #
PIN SYMBOL
FUNCTION
Typical Performance Characteristics
1p
1n
10k
30k
50k
100k
300k
500k
1.0M
f
OSC
OSCILLATOR FREQUENCY (Hz)
4.0
6.0
8.0
10
12
14
16
R
T
)
T
A
=25
°
C
2n
3n
5n
C
T
=0F
V
=
15V
2p
3p
5p
10k
30k
50k
100k
300k
500k
1.0M
f
OSC
OSCILLATOR FREQUENCY (Hz)
38
40
42
44
46
48
50
M
V
CC
= 15V
R
T
= 4.0k
to 16k
C
L
= 15pF
T
A
= 25
°
C
OUT 2
OUT 1
Max. Output Duty Cycle vs. Oscillator Frequency
Timing Resistor vs. Oscillator Frequency
10k
100k
1.0k
10k
100k
1.0M
10M
f, FREQUENCY (Hz)
-20
0
20
40
60
80
100
A
V
,
V
CC
= 15V
V
O
= 1.5V TO 2.5V
R
L
= 100k
T
A
= 25
°
C
GAIN
PHASE
180
150
120
90
60
30
0
P
0
1.0
ERROR AMP OUTPUT VOLTAGE (V)
2.0
3.0
4.0
5.0
7.0
0
0.1
0.2
0.3
0.4
0.5
0.6
V
I
6.0
V
CC
= 15V
T
A
= 125
°
C
T
A
= 25
°
C
T
A
= -55
°
C
Current Sense Input Threshold
vs. Error Amp Output Voltage
Error Amp Open-Loop Gain & Phase vs. Frequency
16 L PDIP & SO Wide
1
SYNC
A positive going pulse applied to this input will synchronize the
oscillator. A DC voltage within the range of 2.4V to 5.5V will inhibit
the oscillator.
2
C
T
Timing capacitor C
T
connects pin to ground setting oscillator fre-
quency.
3
R
T
Resistor R
T
connects to ground setting the charge current for C
T
. Its
value must be between 4.0k and 16k.
4
V
FB1
The inverting input of error amplifier 1. Normally it is connected to
the switching power supply output.
5
COMP
1
Sense
1
V
OUT1
Gnd
The output of error amplifier 1, for loop compensation.
6
Output 1 pulse by pulse current limit.
7
Drives the power switch at output 1.
8
Logic ground
9
Pwr Gnd
Power ground. Power device return is connected to this pin.
10
V
OUT2
Sense
2
COMP
2
V
FB2
Drives the power switch at output 2.
11
Output 2 pulse by pulse current limit.
12
Output of error amplifier 2, for loop compensation.
13
Inverting input of error amplifier 2. Normally it is connected to the
switching power supply output.
14
ENABLE
2
V
REF
V
CC
Output 2 disable. A logic low at this pin disables V
OUT2
.
5.0V reference output. It can source current in excess of 30mA.
15
16
The positive supply of the IC.